29-4

DOMESTIC AND TAVERN TELEGRAPHS.

[Class X.

The hells alone are left in the circuit. When a currentpasses along the wire, the keepers of the electro-magnets,which are on one arm of a lever, are attracted, whichcauses a small hammer on the other arm of the lever tostrike a hell. The clerk who desires to call attentionturns his own bell out of circuit, by moving a lever, and,at the same time, turns his battery and his telegraph in-strument into the circuit, and then leaves them. Thisallows the electric force to have free course, and thedistant hell to ring ; hut the electro-magnet of the alarumis so adjusted that the circuit becomes broken the momentthe armature leaves its normal position, which it does bythe attraction of the magnetism: the magnetism, there-fore, ceases with the cessation of the current, and thearmature returns again to complete the circuit; and soon, alternately, producing a succession of blows uponthe hell. During this time, the telegraph instrument ofthe lirst station, although in the circuit, is perfectly in-active; being so arranged that its electro-magnet is muchless sensitive than that of the alarum, its armature re-quiring more electric force, or more time to acquiremotion, so that the circuit is broken by the action of thealarum before the telegraph has been able to move.When the sounding of the bell has gained attention atthe distant station, the officer in charge there turns hisalarum out of circuit, and introduces his telegraph instru-ment and his battery. There are now in circuit a bat-tery, and an instrument at each station, which are soarranged that the two batteries combine to produce acurrent in one constant direction, and, hence, both actsimultaneously on both instruments.

The instrument presents a circular dial, around whichare engraved the letters of the alphabet, or other con-ventional signals, and is furnished with an index, which,under the conditions above named, continues traversingthe circle at the rate of about thirty times per minute.The two (or more, as the case may be) instruments actprecisely in concert, which is thus accomplished :—

The armature of the electro-magnet carries a lever, atthe end of which is a claw ; that advances one tooth of aratchet-wheel (mounted on the same axis with the index)at every attraction. Hut this armature breaks the circuitat each attraction; and the magnetism ceasing, it isreturned to its normal position by the action of a slightspring, again to complete the circuit, and to draw onone more tooth of the wheel, and cause the index to ad-vance, and so on. All things being in order, the alternatemaking and breaking of the circuit are simultaneous oneach instrument, and the indices of each point to similarletters at the same time. In order to turn this arrange-ment to account, the dial is surrounded by a circle ofstuds corresponding to their respective letters. Onpressing any one of these down, it impedes the progressof the ratchet-wheel just at the time when the circuithas become discontinuous, and no current is passing.The index, therefore, of each instrument rests at theletter in question, and continues its course only when thestud is allowed to return, and the wheel is liberated.

With the following additions this instrument becomesa printing telegraph. The ratchet-wheel is furnished withradii, consisting of springs, each having a type-letter atthe end, directed upwards. In the revolution of thewheel, these types pass between a hammer below and ablackened cylinder above, and between the type and thecylinder passes a band of paper. The hammer is on onearm of a lever, the other arm of which carries the arma-ture of a supplementary electro-magnet, which magnet isin the same circuit with the magnet of the indicatinginstrument. A current passes through the two simulta-neously, but is so instantaneously cut off that the mag-netism has not had time' fully to develop itself and toattract the armature; hut the act of depressing the stud,which causes the index to rest for a moment at a givenletter, is contrived to keep the circuit of the printing mag-net complete during the same interval, and so to allowthe full development of its magnetism, and to cause theattraction of its armature. The type-letter in question ,is at this moment between the hammer and the paperhand. The armature, being powerfully attracted, causesthe hammer to strike a smart blow upward, and then

to press the paper against the blackened cylinder,which prints the form of the letter. Letter after letter isthus printed, and a blank is touched at the end of eachword. When the blanks are struck, the hammer, meetingwith no resistance, moves a little further, and enables alever attached to it to reach a bell, which was beyondits former limit, and thus the sound of a bell is heard atthe end of every word. At the same time that the ham-mer strikes a letter it breaks the circuit of the printingmagnet, and thus liberates itself, and returns to itsnormal position the moment its work is done.

The lever that carries the hammer is likewise providedwith arrangements for advancing the paper the width ofone letter as it returns to its position of rest, so that theletters follow in due succession ; it also advances theblackened cylinder in the direction of its axis, so that itshall not become exhausted by always printing from thesame surface.

There are other arrangements provided for facilitatingthe transmission of electric force to long distances, and forovercoming some of the difficulties that occur in practice.*

A Council Medal was awarded for this beautifulsystem of telegraph.

The remaining foreign Exhibitor—

Stohrkk (Saxony , No. 15, p. 1105), exhibits a mag-neto-electric telegraph. It is applicable to the ordinaryuse of telegraphs. In practice the hand always turnsthe same way. Attached is an alarm bell, which isreadily put in and out of connexion.

A Prize Medal was awarded to Mr. Stohrer.

Domestic Telegraphs.

Burdett (No. 425, p. 455) has exhibited a domestictelegraph, designed to supersede the use of bells inmansions, club-houses, hotels, and large public buildings.The machine itself presents a smooth surface or dial,with various numbers indicated upon it. Every room inthe establishment with which it is in connexion, beingnumbered, is furnished with a wire attached to the cor-responding number of the machine, which has a bellattached to itself. On anyone of the wires being pulled,the fact is indicated by the striking of the bell, theindicators pointingat the same time to the correspondingnumber of the room which requires attendance; beforedoing which, the attendant should replace it, by pressingdown the lever at the foot of the dial; but, shouldseveral indicators on the face of the dial denote thatseveral wires have been pulled at the same time, themachine is so contrived that he may replace them suc-cessively' as they arc attended to. It is intended toobviate the confusion attendant upon the ringiug of anumber of bells at the same time, a source of great per-plexity to the servants ; as the bells having ceasedringing, they are deprived of the means of knowing inwhat part of the house their attendance is required. Themachine is by no means unsightly, and is far less ex-pensive than the ordinary fitting up with bells.

Reid (No. 427, pp. 455, 457) has exhibited a pair ofelectric telegraphs, adapted for the use of hotels, taverns,public, gardens, &c.

Also, another pair, for railway boards, public com-panies, manufactories, See.

A pair of electric telegraphs for domestic purposes,adapted to gentlemen’s dressing-rooms, libraries, orladies’ boudoirs, &c.

Also an electrical apparatus for ringing bells in largemansions, hotels, See. To be brought into immediateaction by pulling a cord or lever, as with common bells.This instrument is designed to act at great distances withease and rapidity.

Whishaw (No. 419, pp. 454, 455) has exhibited adomestic telegraph. The dial, which has an index handaffixed to it, has also engraven upon its face a numberof short sentences or written orders for requisites, suchas arc likely to be called for at the establishment towhich the telegraph belongs. The index points to anyone of these sentences as required, the communication

* For a full description of Siemens and Ilalske’s tele-graph, with plates, see Sehellen, l)er electromagnetischeTelegraph, Braunschweig . 18.50.